Process gas generation for cleaning of substrates

ABSTRACT

Provided is a method and system for cleaning a substrate with a cleaning system comprising a pre-treatment system and a wet clean system. One or more objectives for the pre-treatment system are selected and two or more pre-treatment operating variables including UV dose, substrate temperature, oxygen partial pressure, oxygen and ozone partial pressure, and/or total pressure, are optimized to meet the pre-treatment objectives, using metrology measurements. The substrate includes a layer to be cleaned and an underlying dielectric layer having a k-value. A pre-treatment gas comprising oxygen and/or ozone is delivered onto a surface of the substrate and irradiated with a UV device, generating oxygen radicals. Cleaning of the substrate in the pre-treatment process is set at less than 100% in order to ensure the change in k-value of the substrate is within a set range for the substrate application.

Pursuant to 37 C.F.R. §1.78(a)(4), this application claims the benefitof and priority to prior filed co-pending Provisional Application Ser.No. 61/710,657 entitled “PROCESS GAS GENERATION FOR CLEANING OFSUBSTRATES”, filed on Oct. 5, 2012, which is expressly incorporatedherein by reference.

FIELD

The present application generally relates to semiconductor processingand specifically to a substrate cleaning process comprising apre-treatment process with a process gas and a wet clean process.

RELATED ART

Highly fluorinated polymers are created in reaction ion etch (RIE)patterning processes for low-k dielectrics where k-value is within therange of 2.0-2.6. Ultra-violet (UV) pre-treatment has been demonstratedto improve the polymer removal ability of typical back-end-of line(BEOL) post etch processing using compatible cleaning solvents. UVirradiation in the presence of oxygen has been used for an effectivepre-treatment process prior to a wet clean process. Partial pressures ofoxygen with low pressure ranges have been shown as an effectiveapproach. Low pressure mercury, Hg, lamps are capable of performing thisprocess. Low pressure Hg lamps have two dominant emission wavelengths:254 nm and 185 nm. The 185 nm radiation has sufficient energy tobreak-up oxygen to form oxygen atoms which in turn react with oxygen toform ozone. The 254 nm radiation is absorbed by ozone to generate oxygenatoms. However, use of the 185 nm radiation results in an undesirableincrease in the k-value of the film after processing. The challenge isthat 185 nm radiation has sufficient energy to chemically activate anddestroy the underlying low-k dielectric.

Ozone free Hg lamps are available, (i.e., only 254 nm), but thepre-treatment performance is not as good as ozone generating Hg lamps,(254 nm and 185 nm). Some previous cleaning systems use excimer lamps,for example, one excimer lamp directing the light less than 190 nm intothe oxygen gas causing generation of ozone and another excimer lampdirecting light into the ozone gas, causing generation of an oxygenradical having a high absorption coefficient. Gas including the oxygenradical is passed along the surface of the substrate to causedegeneration of the organic material thereon. Other approaches uselasers that can be generated by an excimer laser which provides UVenergy for driving an oxidation reaction to decompose the resist ororganic materials into byproducts such as CO, CO₂, and H₂O that arecontinuously exhausted by an exhaust pump. Other dry etching techniquescan also be used to clean the substrate but such techniques aretypically followed with a wet clean process. The use of eximer lamps,lasers or the use of thermal ozone process generation requires the useof expensive equipment and processes.

There is a need to clean the post etch polymer while controlling thechange of k-value or damage to the underlying dielectric film in afront-end-of-line (FEOL) or back-end-of-line (BEOL) process. Inaddition, there are needs for (a) reduced cost of ownership for apre-treatment process followed by wet clean process, and (b) asimplified hardware system that reduces the number and complexity ofdelivery systems for process gas and treatment fluids.

SUMMARY

Provided is a method and system for cleaning a substrate with a cleaningsystem comprising a pre-treatment system and a wet clean system. One ormore objectives for the pre-treatment system are selected and two ormore pre-treatment operating variables including UV dose, substratetemperature, oxygen partial pressure, oxygen and ozone partial pressure,and/or total pressure, are optimized to meet the pre-treatmentobjectives, using metrology measurements. The substrate includes a layerto be cleaned and an underlying dielectric layer having a k-value. Apre-treatment gas comprising oxygen and/or ozone is delivered onto asurface of the substrate and irradiated with a UV device, generatingoxygen radicals. Cleaning of the substrate in the pre-treatment processis set at less than 100% in order to ensure the change in k-value of thesubstrate is within a set range for the substrate application.

LIST OF FIGURES

FIG. 1A is an architectural diagram illustrating a prior art method ofresist stripping in a batch etch process.

FIG. 1B is a diagram of a prior art apparatus for removing photoresist(resist) from a substrate using two or more passes of a UV laser beam ina reaction chamber.

FIG. 2 is an exemplary side-view diagram of a polymer film and resistfor low-k samples used in a pre-treatment process using UV light and awet clean process.

FIG. 3 depicts an exemplary graph of the cleaning operating window forsubstrate cleaning as a function of UV dose versus substratetemperature, the substrate cleaning comprising a pre-treatment processusing UV light and a wet clean process using a base oxygen partialpressure.

FIG. 4 depicts an exemplary graph of the cleaning operating window forsubstrate cleaning as a function of UV dose versus substratetemperature, the substrate cleaning comprising a pre-treatment processusing UV light and a wet clean process using a higher oxygen partialpressure than the base oxygen partial pressure.

FIG. 5 depicts an exemplary graph of the cleaning operating window forsubstrate cleaning as a function of UV dose versus substratetemperature, the substrate cleaning comprising a pre-treatment processusing UV light and a wet clean process using a lower oxygen partialpressure than the base oxygen partial pressure.

FIG. 6A depicts an exemplary side-view image of a substrate before theUV irradiation of the substrate with oxygen. FIG. 6B depicts anexemplary side-view image of the substrate after the pre-treatmentprocess. FIG. 6C is an exemplary side-view image of the substrate afterthe pre-treatment process and a wet clean process.

FIG. 7 is an exemplary flow chart for a method of cleaning a substratecomprising a pre-treatment process using UV light and a wet cleanprocess in an embodiment of the present invention.

FIG. 8 is an exemplary flow chart of a method of controlling a cleaningsystem using selected cleaning operating variables in an embodiment ofthe present invention.

FIG. 9 is an exemplary diagram for a cleaning system where the UV sourceis located above a diffusion plate, the diffusion plate configured toblock 185 nm wavelength light and allow other wavelength light toirradiate the substrate during the pre-treatment process and configuredto protect the UV source and associated equipment during the subsequentwet clean process.

FIG. 10 is an exemplary architectural diagram of a cleaning systemdepicting use of a controller for optimizing the operating variables ofthe cleaning system to meet cleaning objectives.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 is an architectural diagram illustrating a prior art method ofresist stripping in a batch etch process. In order to facilitate thedescription of the present invention, a semiconductor substrate isutilized to illustrate applications of the concept. The methods andprocesses equally apply to other workpieces such as a wafer, disk,memory or the like. Similarly, aqueous sulfuric acid and hydrogenperoxide mixture may be utilized to illustrate a treatment liquid in thepresent invention. As mentioned below, other treatment liquids canalternatively be used. The treatment liquid can include primary,secondary, and tertiary chemicals, one or more process gas, and reactionproducts.

Referring to FIG. 1, an architectural diagram 1 illustrating a prior artmethod of surface treatment system such as resist stripping in a batchetch process, where the etch chemicals (etchants) are dispensed usingone or more input streams, 4 and 8, onto the etch processing chamber 9where a plurality of substrates 6 are positioned. The etchants may bereused or recycled or disposed of using the overflow tank 2 and overflowspout 10. Heaters (not shown) can be provided, for example, by havingheaters on the sides or at the bottom of the process chamber 4. Theheaters may be external or inline.

FIG. 1B is a diagram of a prior art apparatus for removing photoresist(resist) from a substrate 14 using two or more passes of a UV laser beam32 in a reaction chamber 16. An apparatus 15 for cleaning a layer oforganic material from substrate 14, such as a resist or polymer, isshown, including a reaction chamber 16, where a supply conduit 20 forprocess gas such as O₂ or O₃ and O₂ are being supplied. The O₃ can begenerated from O₂ input in-situ in an O₃ generator 28 or generated withthe UV laser beam 32. The reaction chamber 16 has the means forgenerating O₃ using UV lamps 36 through quartz windows 48. The lasersource 30 directs the UV laser beam 32 through a focusing lens 38 and atransparent window 40. The substrate 14 containing the layer to becleaned is loaded by a substrate loader 22, moved past the UV laser beam32 by conveyor 26 in the direction of movement 44 and unloaded bysubstrate unloader 24. The method of cleaning is done by moving thesubstrate 14 two or more times past the UV laser beam 32 until thesubstrate 14 is cleaned. Exhaust process gas is continuously pumpedthrough the exhaust conduit 18 by the exhaust pump 34 as indicated bythe exhaust arrows 37.

FIG. 2 is an exemplary diagram 200 of layers of a low-k sample used incleaning a substrate 224 using a pre-treatment process with UV light anda process gas followed by a wet clean process. The substrate 224comprises a silicon layer 216, an advanced low k (ALK) dielectric film212, where the k-value is in the range from 2.0 to 2.2. Other ranges ofthe k-value may also be used. Above the ALK dielectric film 212 isphotoresist 208. The top conformal layer is polymer film 204 in therange of 60 to 70 nm. The cleaning of the substrate includes removal ofthe polymer film 204 and the photoresist 208 by the combinedpre-treatment process and the wet etch process.

FIG. 3 depicts an exemplary graph of the cleaning operating window 308for substrate cleaning as a function of UV dose versus substratetemperature, the substrate cleaning comprising a pre-treatment processusing UV light and a wet clean process using a base oxygen partialpressure. The cleaning operating window 308 is defined as the range ofoperating variables where the one or more objectives of the cleaningprocess are accomplished and where the oxygen partial pressure is keptconstant at the base oxygen partial pressure. The base oxygen partialpressure is selected for the substrate application based on historicalor simulation data. The cleaning operating window 308 is the areabetween the dotted line 316 and the solid line 320 represents points ofUV dose and substrate temperature where the substrate is cleaned withoutany damage to the underlying dielectric. The area 312 bounded by thesolid line 320 until the bottom of the graph represents points of UVdose and substrate temperature where the substrate has residual polymernot removed by the cleaning process. The area 304 bounded by the dottedline 316 and up represents points of UV dose and substrate temperaturewhere the substrate is clean but the underlying dielectric is damaged orwhere the change in k-value exceeds the range of acceptable k-valuechanges. The dotted trend arrows 322 indicate that as the k-value of thedielectric goes down, area 304 tends to expand, i.e., more instances ofclean but damaged substrates. The solid trend arrows 328 indicate thatwith greater post etch polymer thickness, there are more instances ofresidual polymer not being removed by the cleaning process.

FIG. 4 depicts an exemplary graph of the cleaning operating window 408for substrate cleaning as a function of UV dose versus substratetemperature, the substrate cleaning comprising a pre-treatment processusing UV light and a wet clean process using a higher oxygen partialpressure than the base oxygen partial pressure. As mentioned above, thecleaning operating window 408 is defined as the range of operatingvariables where the one or more objectives of the cleaning process areaccomplished and where the oxygen partial pressure is kept constant at avalue higher than the base oxygen partial pressure of FIG. 3. The baseoxygen partial pressure is selected for the substrate application basedon historical or simulation data. The cleaning operating window 408 isthe area between the short-dash line 416 and the long-and-short-dashline 420 represents points of UV dose and substrate temperature wherethe substrate is cleaned without any damage to the underlyingdielectric. The area 412 bounded by the long-and-short-dash line 420until the bottom of the graph represents points of UV dose and substratetemperature where the substrate has residual polymer not removed by thecleaning process. The area 404 bounded by the short-dash line 416 and uprepresents points of UV dose and substrate temperature where thesubstrate is clean but the underlying dielectric is damaged or where thechange in k-value exceeds the range of acceptable k-value changes. Thedotted trend arrows 422 indicate that as the k-value of the dielectricgoes down, area 404 tends to expand, i.e., more instances of clean butdamaged substrates. The solid trend arrows 428 indicate that withgreater post etch polymer thickness, there are more instances ofresidual polymer not being removed by the cleaning process. It should benoted that the area 404 in FIG. 4 where the underlying dielectric isdamaged or where the change in k-value exceeds the range of acceptablek-value changes is a much smaller area than a similar area 304 in FIG.3. In contrast, the area 412 in FIG. 4 where the underlying dielectricis damaged or where the substrate has residual polymer not removed bythe cleaning process in k-value exceeds the range of acceptable k-valuechanges is a much bigger area than a similar area 312 in FIG. 3.

FIG. 5 depicts an exemplary graph of the cleaning operating window 508for substrate cleaning as a function of UV dose versus substratetemperature, the substrate cleaning comprising a pre-treatment processusing UV light and a wet clean process using a lower oxygen partialpressure than the base oxygen partial pressure in FIG. 3. As mentionedabove, the operating window is defined as the range of operatingvariables where the one or more objectives of the cleaning process areaccomplished and where the oxygen partial pressure is kept constant at avalue higher than the base oxygen partial pressure of FIG. 3. The baseoxygen partial pressure is selected for the substrate application basedon historical or simulation data. The cleaning operating window 508 isthe area between the solid line 516 and the long-dash line 520represents points of UV dose and substrate temperature where thesubstrate is cleaned without any damage to the underlying dielectric.The area 512 bounded by the long-dash line 520 until the bottom of thegraph represents points of UV dose and substrate temperature where thesubstrate has residual polymer not removed by the cleaning process. Thearea 504 bounded by the solid line 516 and up represents points of UVdose and substrate temperature where the substrate is clean but theunderlying dielectric is damaged or where the change in k-value exceedsthe range of acceptable k-value changes. The dotted trend arrows 522indicate that as the k-value of the dielectric goes down, area 504 tendsto expand, i.e., more instances of clean but damaged substrates. Thesolid trend arrows 528 indicate that with greater post etch polymerthickness, there are more instances of residual polymer not beingremoved by the cleaning process. It should be noted that the area 504 inFIG. 4 where the underlying dielectric is damaged or where the change ink-value exceeds the range of acceptable k-value changes is a much largerarea than a similar area 304 in FIG. 3. In contrast, the area 512 inFIG. 4 where the underlying dielectric is damaged or where the substratehas residual polymer not removed by the cleaning process in k-valueexceeds the range of acceptable k-value changes is a much smaller areathan a similar area 312 in FIG. 3.

FIGS. 3, 4, and 5 highlight that the cleaning operating windows, (308,408, and 508), are correlated at least to substrate temperature, UV dosein the pre-treatment process, oxygen partial pressure, total pressure,and the process gas used. The ranges of operating variables that causedamage to the underlying dielectric or cause incomplete polymer cleaningchanges as these operating variables are changed. The change in k-valueis a critical parameter that is selected for the substrate application.The k-value is the extinction coefficient and is related to the decay,or damping of the oscillation amplitude of the incident electric fieldof the dielectric underlying layer. The extinction coefficient k of alayer of the underlying dielectric layer, (k-value), is a function ofsubstrate temperature and the pre-treatment process gas used. When UVlight is not used, i.e., there is no pre-treatment process, the k-valueof the underlying dielectric can be used as a base value for measuringthe change in k-value. The k-value of the underlying dielectric layer asfunction of the oxygen gas partial pressure and can be measured withoptical metrology devices such as reflectometers or ellipsometers.Methods and techniques for extracting k-value from reflectometer orellipsometer measurements are well known in the art. The change ink-value of the layer of the substrate is jointly correlated to substratetemperature, the process gas used, the oxygen partial pressure, thetotal process gas pressure, and the UV dose. Thus, these cleaningoperating variables need to be controlled to perform the cleaning andalso meet an acceptable change in k-value target.

FIG. 6A depicts an exemplary side-view image 600 of a substrate beforethe UV irradiation of the substrate in a test. The side-view image 600of a repeating structure after a post-etch process and prior to thetwo-step cleaning method comprising a pre-treatment UV irradiationprocess and a subsequent wet clean process. The repeating structure 604is characterized by the width 608 and a height 612. FIG. 6B depicts anexemplary side-view image 630 of the substrate after the pre-treatmentUV irradiation. Cleaning of the substrate layer starts as evidenced bythe smaller width 638 and a higher height 642. FIG. 6C is an exemplaryside-view image 660 of the substrate after the pre-treatment UV processand the subsequent wet clean process are complete. Cleaning of the postetch substrate is substantially complete as evidenced by the removal ofthe polymer and resist layers (layers 204 and 208 in FIG. 2), and thetarget critical dimensions, such as the target width 672 and the targetheight 668, are achieved.

It is known in the art that the sole use of the wet clean process doesnot consistently clean the polymer completely. The pre-treatment processusing UV light coupled with the wet clean process has proved to increasethe operating window of the cleaning chemistry to remove challengingpost etch polymer. As the residues at the back-end-of line include morefluorinated residue, it is more difficult to remove this residue withwet chemistry alone. Several technical trends increase the potentialvalue of the UV pre-treatment. First, due to the lower k-value of filmwith increased porosity and changes in film deposition and cure, the useof the pre-treatment UV irradiation makes the film more sensitive tocleaning chemistry. Specifically for reactive ion etching (RIE), theprocess development due to ultra-low k (ULK) materials and scaling oforganic residue leads to post etch polymer composition changes thatrequire expensive and time consuming reformulation of the post etchclean chemistry. This time consuming reformulation can be avoided usingthe two step method described in this application. The inventor foundthat the pre-treatment process using UV light and process gas cancompletely perform 100% cleaning of the polymer. In this invention, thepercentage of cleaning with the pre-treatment process is intentionallyset to less than 100 percent in order to minimize the change in thek-value of the underlying dielectric or keep the k-value change insidethe acceptable range for the substrate application. The goal of thepre-treatment process is not to completely remove the polymer layer butto chemically modify the post etch polymer to make it easier to removewith a wet clean process while eliminating damage to the underlyingdielectric. Optimization of the two or more operating variables in thepre-treatment process allows for a more consistent completion ofcleaning of the substrate by a subsequent wet clean process.

FIG. 7 is an exemplary flow chart 700 for a method of cleaning asubstrate using a pre-treatment process using UV light and a wet cleanprocess in an embodiment of the present invention. In operation 704, oneor more pre-treatment objectives are selected for a pre-treatment systemof a cleaning system. Examples of pre-treatment objectives includepre-treatment cleaning percentage, pre-treatment first process time,total cost of ownership, change of k-value, and the like. Thepre-treatment cleaning percentage can be in the range of 50 to 99%, thefirst process time can be 120 seconds or less, and the change in k-valuecan be 0.2 or less. In operation 708, two or more pre-treatmentoperating variables are selected and optimized towards achieving the twoor more pre-treatment objectives. The selected two or more pre-treatmentoperating variables can include two or more of UV dose, substratetemperature, pre-treatment cleaning percentage, oxygen partial pressure,oxygen and ozone partial pressure, first process time, or total processgas pressure. The UV dose can be in a range from 0.1 to 20.0 J/cm2, theoxygen partial pressure can be from 15 to 159 Torr, the total processgas pressure can be 80 to 760 Torr, the substrate temperature can befrom 25 to 150 ° C., and the k-value of the underlying dielectric can befrom 2.0 to 2.6.

In operation 712, a substrate having a layer to be cleaned and anunderlying dielectric layer is provided for processing, the underlyingdielectric having a k-value. In operation 716, a pre-treatment processgas is delivered onto a surface of the substrate in the processingchamber of the cleaning system, using a gas delivery system. The processgas can include oxygen or oxygen and ozone at a specific ratio of ozoneto oxygen. Alternatively, the process gas can be filtered air or cleandry air (CDA). In operation 720, the process gas is irradiated with a UVdevice to generate radicals for a pre-treatment of the substrate, wherethe irradiation is completed during a pre-treatment first process time,and the UV device having one or more wavelengths and a UV dose. Inoperation 724, the selected two or more pre-treatment variables arecontrolled using the selected two or more metrology measurements in thepre-treatment system in order to meet the one or more pre-treatmentobjectives. In operation 728, a wet clean process is performed on thesubstrate using the wet clean system. The wet clean system can use avariety of chemistries including sulfuric acid and hydrogen peroxide(SPM), SPM with ozone (SPOM), phosphoric acid and steam, ammoniumhydroxide and hydrogen peroxide, dilute hydrofluoric acid (DHF),deionized water and ozone, dimethyl sulfoxide and monoethanol amine(DMSO/MEA), or other wet clean chemistries.

FIG. 8 is an exemplary flow chart 800 of a method of controlling acleaning system using selected cleaning operating variables in anembodiment of the present invention. In operation 804, measurements forcalculating a value of the one or more pre-treatment objectives areobtained. The measurements can include obtaining the top view images ofthe substrates during the pre-treatment process to check the cleaningprogress, check the percentage of post etch polymer removal, check theelapsed first process time, check the composition of the process gas, UVdose, or the rotation speed of the substrate. In operation 808, thecalculated values of the one or more pre-treatment objectives arecompared with the set one or more pre-treatment objectives. Calculationof the values of the one or more pre-treatment objectives can includecalculating the change in k-value, the percentage of cleaning in thepre-treatment process, or the cost of ownership based on projected unitthroughput of substrates. In operation 812, if the one or moreobjectives are not met, the two or more selected operating variables areadjusted until the one or more pre-treatment objectives are met. Forexample, the UV dose can be adjusted to increase or decrease thepercentage of cleaning in the pre-treatment process. The substratetemperature, the flow rate of oxygen and/or ozone, or partial pressureof the oxygen and/or ozone may be adjusted to increase the oxygenradical or atomic oxygen in the process gas or the ratio of ozone tooxygen. The first process time may be shortened to minimize change ofk-value or lengthened to ensure higher percentage of cleaning.

FIG. 9 is an exemplary diagram 900 for a cleaning system 902 where theUV source 904 is located above a diffusion plate 924, the diffusionplate 924 configured to block 185 nm wavelength light to irradiate thesubstrate 932 during the pre-treatment process and protect the UV source904 and associated equipment during the subsequent wet clean process.The process gas 912 can comprise oxygen and/or nitrogen. Alternatively,the process gas can comprise oxygen and/or nitrogen and/or ozone. Inanother embodiment, fan filter unit (FFU) air or CDA 920 can beintroduced into the process chamber 916 as the process gas during thepre-treatment process. During the wet clean process, the treatmentliquid 944 delivered into the process chamber 916 by delivery device 936onto the substrate 932, where the treatment liquid 944 and the processgas 912 or 920 are removed through exhaust units 940, 928. The systemhardware for the substrate cleaning system is simplified because thereis no requirement for an external oxygen or ozone containing oxygen gasfeed into the UV chamber. Processing with standard air has demonstratedthe ability to generate sufficient ozone and oxygen atoms for thepre-treatment process to work. Feeding oxygen or ozone carrying gaslines increases tool cost because of the associated hardware designsafety requirements. The inventor found out that significantly shorterUV exposure times can be realized by the combined pre-treatment processusing UV and a process gas followed by a wet clean process. Further, theinventor was also able to shorten the wet clean process time. Moreover,the generation of in-situ process gas also reduces the number of UVsources employed in the design of the substrate cleaning system. Forexample, all UV hardware in FIG. 9 is contributing directly to thecleaning of the substrate, ultimately to the generation of atomicoxygen.

Referring to FIG. 9, an embodiment of the invention includes an indirectsource of ozone generated either by vacuum UV (VUV) sources (<200 nm),corona discharge or UV source with wavelengths below 200 nm fed into thesubstrate processing chamber while under irradiation with 254 nm onlyradiation. The absorption of the radiation by the ozone initiates theformation of oxygen atoms at the substrate surface that enable thedamage-free cleaning of substrates. Alternatively, in anotherembodiment, the substrate is irradiated with ozone emitting UV where an185 nm absorbing filter is placed between the substrate with geometrythat prevents direct and indirect illumination with 185 nm but allows adiffusion path for ozone to reach the substrate surface. Mass transportof the process gas can be enhanced by flowing the oxygen filledatmosphere through the <200 nm wavelength absorbing gas diffusion plate.

FIG. 10 is an exemplary architectural diagram 1000 of a cleaning system1004 depicting use of a controller 1090 for optimizing the operatingvariables of the cleaning system 1004 towards meeting the one or morepre-treatment objectives. The cleaning system 1004 can use two or moreoptical metrology devices 1008. An optical emission spectroscopy (OES)device 1070 can be coupled to the processing chamber 1010 at a positionto measure the optical emission from the processing region 1015. Inaddition, another set of optical metrology devices 1060 can be disposedatop the processing chamber 1010. Although four optical metrologydevices are shown, many other alternative and different configurationsof the optical metrology devices can be positioned to implement designobjectives using a plurality of optical metrology devices. The fouroptical metrology devices can be spectroscopic reflectometric devicesand/or interferometric devices. The measurements from the two or moreoptical metrology devices, for example, the OES device 1070 and the setof optical metrology devices 1060, are transmitted to the metrologyprocessor (not shown) where one or more critical dimension values areextracted. Measurements can be performed with the one or more opticalmetrology device OES 1070 and/or the set of optical metrology devices1060 and one or more etch sensor devices, 1064 and 1068.

As mentioned above, a process sensor device, for example, can be aresidue sensor device 1064 measuring the percentage of residueremaining, or measuring a cleaning operating variable with a substantialcorrelation to percentage of residue removal. Another process sensordevice can include a device measuring the partial pressure of oxygen orthe oxygen and ozone partial pressures or the total pressure of theprocess gas. Selection of at least one or more process sensor devicescan be done using multivariate analysis using sets of process data,metrology data (diffraction signals) and process performance data toidentify these inter-relationships. The measurements from the two ormore optical metrology devices, for example, the OES device 1070 and theset of optical metrology devices 1060 and the measurement from thesensor device 1064 and/or 1068 are transmitted to the metrologyprocessor (not shown) where the operating variable values are extracted.

Still referring to FIG. 10, the cleaning system 1004 includes acontroller 1090 coupled to sub-controllers in the two or more opticalmetrology measurement devices 1009 comprising a plurality of opticalmetrology devices 1060, optical emission spectroscopy (OES) device 1070,and one or more etch sensor devices, 1064 and 1068. One or more chemicalmonitors 1092 can be coupled to the processing chamber to ensure theprocess gas is within the ranges set. Another sub-controller 1094 can beincluded in the motion control system 1020 that is coupled to thecontroller 1090 and can adjust the first and second speed of therotation of the motion control system for a single substrate tool. Thecontroller 1090 can be connected to an intranet or via the Internet toother controllers in order to optimize the cleaning operating variablesand in order to achieve the one or more pre-treatment objectives.

Although only certain embodiments of this invention have been describedin detail above, those skilled in the art will readily appreciate thatmany modifications are possible in the embodiments without materiallydeparting from the novel teachings and advantages of this invention. Forexample, although one exemplary process flow is provided for cleaning ofsubstrates, other process flows are contemplated. As also mentionedabove, the cleaning method and system of the present invention can beused in an FEOL or BEOL fabrication cluster. Accordingly, all suchmodifications are intended to be included within the scope of thisinvention.

What is claimed:
 1. A method for cleaning a substrate in a cleaningsystem, the cleaning system comprising a pre-treatment system and a wetclean system, the pre-treatment system including a processing chamberand a gas delivery sub-system, the method comprising: selecting one ormore objectives for the pre-treatment system; selecting two or morepre-treatment operating variables to be optimized for achieving the oneor more pre-treatment objectives; providing a substrate having a layerto be cleaned and an underlying dielectric layer, the underlyingdielectric layer having a k-value; delivering a pre-treatment gas onto asurface of the substrate in the processing chamber using the gasdelivery sub-system; and irradiating the pre-treatment gas with anultra-violet (UV) device and generating radicals for pre-treatment ofthe substrate, the irradiation completed during a pre-treatment firstprocess time, the UV device having one or more ranges of wavelengths anda UV dose; and controlling the selected two or more pre-treatmentvariables using obtained one or more metrology measurements in thepre-treatment system; wherein the pre-treatment gas comprises oxygen oroxygen and ozone and wherein the two or more pre-treatment operatingvariables comprises two or more of the light UV dose, substratetemperature, first process time, oxygen partial pressure, oxygen andozone partial pressure, and/or total process gas pressure; and whereinthe one or more pre-treatment objectives include a pre-treatmentcleaning percentage that is less than 100 percent.
 2. The method ofclaim 1 wherein the one or more pre-treatment objectives includes atarget total cost of ownership for the pre-treatment system and the wetclean system or a target change in k-value.
 3. The method of claim 1wherein the pre-treatment cleaning percentage is in a range from 50 to99 percent.
 4. The method of claim 1 wherein the pre-treatmentirradiation duration is less than 120 seconds.
 5. The method of claim 1wherein the pre-treatment cleaning percentage is in a range from 50 to99 percent and the pre-treatment irradiation duration is less than 120seconds.
 6. The method of claim 1 wherein the one or more pre-treatmentobjectives includes a target total cost of ownership of thepre-treatment system and the wet clean system, first process time, andchange of k-value.
 7. The method of claim 1 wherein: the total cost ofownership for the combined pre-treatment system and wet clean system isless than the cost of cleaning the substrate using a wet clean systemonly; the first process time is less than 120 seconds; and/or the changeof k-value of the underlying dielectric is 0.2 or less.
 8. The method ofclaim 1 wherein the delivering the pre-treatment gas utilizes ozone andoxygen atoms generated from air, or oxygen with an indirect source ofozone, wherein the ozone is generated by vacuum UV sources or a coronadischarge.
 9. The method of claim 8 where the ozone is generated by a UVsource with wavelengths below 240 nm fed into the processing chamberwhile the substrate is under irradiation with 254 nm only radiation. 10.The method of claim 1 wherein the UV device is one or more low pressureHg lamps.
 11. The method of claim 10 wherein the UV device has two lightwavelength ranges, the first dominant light wavelength is 185 nm and thesecond dominant light wavelength is 254 nm.
 12. The method of claim 10wherein the UV device utilizes a diffusion plate to absorb the 185 nmirradiation.
 13. The method of claim 1 wherein the k-value of thedieletric layer is in the range of 2.0 to 2.6 and/or the substratetemperature is in a range from 25 to 150 degrees C.
 14. The method ofclaim 1 wherein the oxygen partial pressure is in a range of 15 to 159torr and/or the total process gas pressure is in a range from 80 to 760Torr.
 15. The method of claim 1 wherein the UV dose is in a range from0.1 to 20.0 J/cm².
 16. The method of claim 1 further comprisingperforming a wet clean process using the wet clean system, aftercompletion of the pre-treatment process.
 17. The method of claim 16wherein the wet clean process is performed on a single wafer system. 18.The method of claim 16 wherein the pre-treatment process is performedusing first single wafer system and the wet clean process is performedusing a second single wafer system or wherein the pre-treatment processand the wet clean process are performed using the same single wafersystem.
 19. The method of claim 16 wherein the wet clean system isperformed using an immersion clean process with a treatment liquid forthe wet clean process, the immersion clean process using aqueous,semi-aqueous, or full solvent chemistry.
 20. The method of claim 19where the treatment liquid comprises one or more of ammonium hydroxide(NH₄OH) and hydrogen peroxide (H₂O₂), dilute hydrogen fluoride (DHF),deionized water (DIW) and ozone (O₃), or dimethyl-sulfonide (DMSO) ormono-ethylamine (MEA).
 21. The method of claim 20 further comprisingrecycling the treatment liquid.
 22. The method of claim 1 wherein thecleaning system is part of a front-end-of-line fabrication cluster or aback-end-of-line fabrication cluster.
 23. The method of claim 9 whereinthe pre-treatment gas is delivered and mixed in the processing chamberand wherein the UV source is located above a diffusion plate, thediffusion plate configured to block 185 nm wavelength light fromirradiating the substrate during the pre-treatment process and toprotect the UV source and associated equipment during the subsequent wetclean process.
 24. The method of claim 9 wherein the processing chamberis configured to function as a reaction chamber during the pre-treatmentprocess and during the subsequent wet clean process.
 25. A system forcontrolling cleaning of a layer on a single substrate, the systemcomprising: a substrate having a layer comprising an ion implantedresist and a polymer film, the substrate having a k-value; a substratecleaning system configured to perform a pre-treatment process and a wetclean process, the substrate cleaning system comprising: a processingchamber configured to hold the substrate; a process gas delivery systemcoupled to the processing chamber and configured to deliver one or moreprocess gases onto a portion of a surface of the substrate during afirst process time; an ultra-violet (UV) device coupled to theprocessing chamber and configured to irradiate the surface of thesubstrate for a first process time with a UV light, the UV device havingone or more wavelength ranges and a UV dose; a treatment liquid deliverysystem coupled to the processing chamber and configured to deliver atreatment liquid onto the surface of the substrate during a secondprocess time; a motion control system coupled to the processing chamberand configured to provide the substrate a first motion speed during thefirst process time and a second motion speed during the second processtime; a substrate temperature adjustment device coupled to theprocessing chamber and configured to adjust the substrate temperature; acontroller coupled to the substrate cleaning system and configured tooptimize two or more pre-treatment operating variables in order toachieve one or more pre-treatment objectives.
 26. The system of claim 25wherein the one or more pre-treatment objectives comprises a percentageof polymer film removal and a total time, the total time being the sumof the first process time and the second process time.
 27. The system ofclaim 25 wherein the one or more process gases is a mixture of oxygenand ozone and the treatment liquid is a sulfuric acid peroxide mixture(SPM), the wavelength of the light from the UV device is in a range of200 to 300 nm.
 28. The system of claim 25 wherein the one or moreprocess gases is oxygen and ozone, the UV device is one or more lowpressure Hg lamps, and the treatment liquid is SPM.
 29. The system ofclaim 28 wherein the ozone and oxygen atoms are generated from air, oroxygen with an indirect source of ozone, wherein the ozone can begenerated by vacuum UV sources, corona discharge, or UV source withwavelengths below 200 nm fed into the processing chamber while thesubstrate is under irradiation with 254 nm only radiation.
 30. Thesystem of claim 29 wherein oxygen and ozone are delivered and mixed inthe processing chamber and wherein the UV source is located above adiffusion plate, the diffusion plate configured to block 185 nmwavelength light to irradiate the substrate during the pre-treatmentprocess and protect the UV source and associated equipment during thesubsequent wet clean process.
 31. The system of claim 29 wherein theprocessing chamber is a combined processing chamber configured tofunction during the pre-treatment process and during the subsequent wetclean process.
 32. The system of claim 29 further comprising a recyclesystem coupled to the processing chamber and configured to recycle thetreatment liquid.
 33. The system of claim 29 wherein the selected two ormore operating variables of the pre-treatment process include two ormore of UV dose, substrate temperature, pre-treatment cleaningpercentage, oxygen partial pressure, oxygen and ozone partial pressure,first process time, or total process gas pressure.
 34. The system ofclaim 33 wherein the UV dose is in a range from 0.1 to 20.0 J/cm2, theoxygen partial pressure is from 15 to 159 Torr, the total process gaspressure is from 80 to 760 Torr, and/or the substrate temperature isfrom 25 to 150 C.
 35. The system of claim 34 where the k-value of theunderlying dielectric is from 2.0 to 2.6 and/or the target change ink-value is 0.2 or less.